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MR.  R.  OWEN  ON  THE  OSTEOLOGY  OF 
separates  it  in  the  upper  jaw  from  the  small  deciduous  incisors,  which,  together  with 
the  laniary  tooth,  are  partially  protruded  from  their  sockets.  The  large  foramina  behind 
the  incisor  and  laniary  teeth  aflFord  a  sure  indication  of  the  presence  of  the  permanent 
series,  which  are  still  concealed  within  the  jaws  ;  and  these  are  found,  upon  a  removal 
of  the  parietes  of  the  alveoli,  lodged  in  the  following  order. 
In  the  upper  jaw  the  second  or  smaller  incisor  is  the  most  advanced  in  its  progress, 
its  middle  projecting  point  being  just  within  the  orifice  leading  to  the  cavity  in  which 
it  is  lodged.  Its  posterior  surface  is  directed  inwards,  or  mesiad,  and  is  placed  at  right 
angles  to  the  corresponding  surface  of  the  first  or  great  incisor,  immediately  behind 
which  it  is  situated,  and  from  which  it  is  separated  by  a  thin  lamella  of  bone.  The 
entire  crown  and  about  half  a  line  of  the  fang  are  formed.  The  great  crown  of  the  first 
incisor  has  almost  a  horizontal  position,  and  occupies  the  whole  breadth  of  the  as  in- 
cisivum. 
Behind  the  second  incisor  comes,  not  the  laniary,  but  the  crown  of  the  first  bicuspis, 
separated  from  the  incisor  by  a  lamina  of  bone  about  a  line  in  thickness.  Then,  deeper 
in  the  jaw  and  posterior  to  the  first  bicuspis,  is  the  crown  of  the  second  bicuspis.  In  each 
of  these  about  one  third  of  a  line  of  the  fang  is  already  formed.  The  first  true  molar  has 
already  taken  its  place  in  the  dental  series  ;  but  its  recent  formation  is  shown  in  the 
shortness  of  the  fangs  and  the  wide  entry  to  their  cavity,  in  which  the  pulp  was  con- 
tained. The  crown  only  of  the  second  true  molar  is  formed,  which  is  lodged  deep  in 
the  j^iw,  with  the  grinding  surface,  as  in  the  undeveloped  teeth  of  the  Elephant,  directed 
backwards  in  the  upper  jaw,  and  forwards  in  the  lower.  This  surface  has,  however,  all 
the  characteristic  markings  of  the  corresponding  tooth  in  the  old  Orang.  A  large  round 
foramen  leads  to  the  concealed  cavity  in  which  it  is  lodged.  The  socket  of  the  third 
molar,  or  dens  sapientioe,  is  widely  open,  but  contains  as  yet  only  a  little  shrivelled 
membrane  with  specks  of  calcareous  matter,  the  remains  of  the  pulpy,  and  commence- 
ment of  the  bony,  rudiments  of  the  future  tooth. 
In  the  lower  jaw  the  crowns  of  the  permanent  teeth  are  situated  in  nearly  the  same 
relative  position  as  in  the  upper.  The  second  incisor  is  immediately  behind  and  a  little 
above  the  first.  The  conical  extremity  of  the  crown  of  the  great  laniary  is  lodged  deep 
in  the  jaw,  with  the  apex  projecting  into  the  interval  between  the  second  incisor  and 
first  bicuspis.  The  crowns  of  the  bicuspides,  which  in  the  upper  jaw  have  the  grinding 
surface  directed  outwardly,  in  the  lower  jaw  have  the  same  surface  turned  in  the  oppo- 
site direction.  The  great  crown  of  the  second  molar  is  equally  advanced  with  that  of 
the  upper  jaw ;  and  in  like  manner,  of  the  third  molar,  the  cavity  only  and  a  small 
shrivelled  rudiment  remain. 
It  is  impossible  to  contemplate  the  apparent  confusion  in  which  these  huge  succes- 
sors of  the  temporary  teeth  are  crowded  in  the  jaws,  without  a  feeling  of  surprise  and 
admiration  at  the  regular  arrangement  they  present  when  their  evolution  is  completed. 
It  would  seem  as  if  the  incisors  must  have  taken  up  the  same  relative  position  as  those 
